Conventionally, there is known a lane mark recognition apparatus for recognizing a lane mark for traffic lane division provided on a road from a color image obtained by an in-vehicle camera for capturing a road ahead of a vehicle (for example, refer to Japanese Patent Laid-Open No. 2002-123819).
The conventional lane mark recognition apparatus converts a color signal of each pixel in the color image to a luminance signal with a difference between the lane mark and portions other than the lane mark emphasized in order to detect the lane marks, a white line and a yellow line.
If the luminance of the color image is high, however, the yellow line cannot be extracted at the time of conversion to the luminance signal according to the circumstances of the road in some cases. Therefore, it is desired to improve the performance of detecting lane marks in the case where there are lane marks different in color such as the white line and the yellow line.